Daniell battery made by Elliott Bros. John Frederic Daniell (1791-1845) was the first Profesor of Chemistry at King's College, London. This type of cell was invented by him in 1836 and was the first two-fluid arrangement, in which one fluid acted as electrolyte and the other as a depolariser. It was used by all the emerging British and American commercial telegraph systems because the current produced was stronger and more constant. The Voltaic pile and similar batteries had a tendancy to polarise and almost stop producing current after a while.
© Science Museum / Science & Society Picture Library